LapTimer has been designed for track days at UK racing circuits. It has a list of most UK Circuits with track and contact details, but it does have the option to set your own lap lengths.

Once you have selected the track you are racing on, the stop watch is designed to be easily used with a large "Lap" button. For each lap your time & average speed is recorded. Your best lap time & speed is also displayed.
It does NOT use GPS to workout when you have complete lap as I have found them not to 100% accurate on some tracks especially at speed.
When you have finished racing you can review all the laps and even e-mail the results.

Features.
- Most of the UK race track information is included (More can be added if I have missed any! please tell me).
- Set your own lap length, so can be used for any circuit.
- Set your own lap time to work out average speed with out using the stopwatch.
- E-mail your results, to review them later or to show off

Because the stopwatch is manual (ie does not use GPS to trip the lap times) it is advisable to have your iphone on a proper mount in you car or have a passenger (The mount option is much lighter!)